224 J- MCA. KATER. 



PLATE n. 



FIG. 10. Interphase nucleus from the meristematic tissue at the tip of the root. 

 Disperse chromatin granules around the periphery of the nucleus. Linin sheaths 

 of chromosomes prominent. 



FIG. ii. Resting nucleus from slowly growing region of the root. Nucleolus 

 smaller than in interphase and disperse chromatin so abundant that the linin strands 

 are obscured. 



FIG. 12. Cell from the radicle of a dry mature bean embryo. Disperse chro- 

 matin has disappeared. Linin sheaths of chromosomes are very prominent. 



FIG. 13. Resting cell illustrating poor fixation by Flemming's solution, except- 

 ing a few peripheral layers of cells. 



FIG. 14. Early prophase. The disperse chromatin granules are becoming 

 larger, fewer, and stain more darkly. 



FIG. 15. Prophase continued. The disperse granules are larger and a heavy 

 band of chromatin is appearing along the linin strands. 



FIG. 16. A continuation of processes illustrated in Fig. 15. 



FIG. 17. The chromosomal vesicles on one side of the nucleus have lost all 

 achromatic material and are contracting to form chromosomes. Note that the 

 nuclear membrane of the other side is continuous with the nearest formed chromo- 

 somes. 



FIGS. 18, 19 AND 20. Further steps in the contractions of chromosomal vesicles 

 and separation of the chromosomes. 



FIGS. 21 AND 22. Drawings showing the chromosome elements in three dimen- 

 sions. Compare 21 to 17 and 22 to 19. 



